Sampling of pigging debris was performed from three multiphase pipelines that previously were exposed to microbiologically influenced corrosion (MIC) due to high abundances of sulfate-reducing prokaryotes (SRP) and methanogens. Sampling was also performed from a water injection pipeline to investigate differences in the microbial community. Quantification of microorganisms using qPCR analysis revealed that numbers of SRP and methanogens were in the range of 103 to 105 cells/g in the multiphase pipelines and 103 to 105 cells/ml in the water injection pipeline. The metabolic activity determined by RT-qPCR was relative low. NGS sequencing analysis detected Methanothermococcus to be most active in multiphase pipelines and Desulfohalobiaceae in the water injection pipeline as potentially hydrogen-scavenging and MIC-causing microorganisms. Further, Methanocalculus and Desulfovibrio were found in significant proportions showing that methanogens were the major MIC-causing microorganisms in multiphase pipelines and sulfate- reducing bacteria in injection water pipelines. The MIC risk was determined to be low when quantified using the pre-established company model, due to low bacterial numbers present in the samples. By combining qPCR, RT-qPCR, and NGS we were able to provide a more accurate MIC analysis, though, the application of molecular microbiological methods needs further development to improve and validate sampling procedures, methodology, and data interpretation for determining MIC factors.

Subject
Archaea, Water, Microbial communities, Methanogens, Pipelines, Bacteria, Water injection, Pigging, Microorganisms, Microbiologically influenced corrosion, Hydrogen, Samples, Sampling
Keywords:
Pipelines, Microbiologically Influenced Corrosion (MIC), Mitigation, Danish Sector of the North Sea, sulfate-reducing Bacteria (SRB), methanogens, qPCR, Reverse Transcriptase qPCR (RT-qPCR), cell specific activity (CSA) index, next generation sequencing (NGS)
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2018
Association for Materials Protection and Performance (AMPP)
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